smith



2 Sheets-:Sheet 1.

(N0 Mudel.) W. MSMITH.

RELIEF VALVE FOR LOCOMOTIVES.

No. 425,265. Patented Apr. 8, 1890.

I" .1. F W h n (No Model.) 2 Sheets-Sheet 2.

W. M. SMITH.

RELIEF VALVE FOR LOCOMOTIVES.

Patented Apr. 8, 1890.

UNITED STATES PATENT Fries,

lVALTER MACKERSIE SMITH, OF JESMOND, NEVVCASTLE-UPON-TYNE, COUNTY OFNORTHUMBERLAND, ENGLAND.

RELIEF-VALVE FOR LOCOMOTIVES.

SPECIFICATION forming part of Letters Patent No. 425,265, dated April 8,1890.

Original application filed July 3, 1889, Serial No. 316,477. Divided andthis application filed September 3, 1889. Serial No. 322,817. (Nomodel.) Patented in England January 11, 1889, No. 571; in France June 5,1889, No. 198,750, and in Belgium June 5,

To all whom it may concern.-

Be it knownth at I, WALTER MAOKERsIE SMITH, a subject of the Queen ofGreat Britain and Ireland, residing at Jesmond, Newcastle-upon-Tyne, inthe county of Northumberland, England, have invented certam new anduseful Improvements in Relief-Valves for Locomotive-Engines, (for whichpatents have been obtained in England, No. 571, dated IO January 11,1889 in France, No.198,750, dated June 5, 1889, and in Belgium, No.86,529, dated June 5, 1889,) of which the following is a specification.D

This application is filed as a division of my I 5 pending applicationfor United States patent,

filed July 3, 1889, Serial No. 316,477.

This invention has for its object improvements in locomotive-engines.

Balanced valves have been used for distributing steam in most classes ofengines. In marine and other engines they always work under pressure ofsteam, whereas locomotiveengines when descending inclines have theirmomentum kept up by the action of gravity and continue to move aftersteam has been shut off. Assuming balanced valves, includingpiston-valves, to be employed instead of the ordinary slide valves, theactlon of these valves may be compared to what would occur assuming anordinary slide-valve to be used that could not rise or lift off theface; hence by the action of the engine piston steam would be exhaustedfrom the steampipe and steam-chest, and, the valve not be- 3 5 ing ableto lift, no air could pass from the atmosphere into the steam-chest,except the small quantity that would pass in at the end of each stroke,and which would be qulckly drawn out again by the recedlng piston. Inconsequence the engine would be unnecessarily retarded. Air passing downthe exhaustpipe would press on the piston 1n the opposite direction tothat in which it mlght be moving, and this pressure not being nearlycounterbalanced by that due to the rarefied air pressing on the opposlteside of the piston,

' there would result undue tension of the piston-rod and connectionsdurlng the backward stroke and undue compression during the forwardstroke. Now, according to this invention, the foregoing disadvantagesare obviated by admitting steam alone in an automatic manner to thesteam chest or cylinder of a locomotive which is running with the steamshut 0%. To this end the steam is admitted 5 5 automatically to thesteam-chest and thence to the cylinder by a suitable valve or valvesopened or caused to open by the pressure of the atmosphere when thepressure within the steam chest or cylinder falls below that of theatmosphere. The steam so admitted acts as would steam admitted in theusual Way from the boiler, and thus serves to prevent rarefaction in thesteam chest and cylinder, so that at least a pressure equivalent, orapproximately so, to that of the atmosphere is exerted on both sides ofthe piston until the distributing-valve cuts off communication with thatpart of the cyl inder behind the receding piston, when the inclosedsteam will expand, decreasing in pressure. Toward the end of the strokethespace in the cylinder on the opposite side of the piston by the samemeans has its communication out off from the exhaust, the 7 5 steambeing then compressed and forming a cushion which arrests the movementof the piston, thereby obviating undue strain such as hereinabovereferred to. A similar result might be obtained by admitting steamdirect to the cylinder without passing through the steam-chest, when thepressure of the fluid exerted on the back of the receding piston wouldvary little throughout the stroke. The steam is caused to be admitted inlimited quantities when the main supply of steam is shut off at theregulator. To this end a piston is employed, or its equivalent, subjecton one side to the atmospheric pressure and on the other side to thepressure in the steam 0 chest or cylinder. This piston is arrangedtooperate a valve-it may be a clack-valve or a piston-valve-whieh controlsthe connection between the steam chest or cylinder and the boiler. lVhenthe atmospheric pressure is 5 greater than the pressure in the steamchest partly in elevation, so much of a locomotive-- engine as isnecessary to illustrate the application thereto of apparatus accordingto this invention for automatically admitting steam alone to thesteam-chests of the cylinders.

Fig. 2 shows in longitudinal vertical section, to an enlarged scale, oneof the apparatus detached, the steam-valve and part of the airactuatedpiston being shown in elevation.

Fig. 3 is an end elevation of the apparatus.

Fig. 4 is a transverse section on the line 0 P. 1

Referring to Fig. 1, 1 is one of the workingcylinders of the engine, and2 the steam-chest of such cylinder.

3 3 are liners in the steam-chest.

the example shown.

4 4 are live-steam spaces. 5 is an exhaust-steam space. 6 6 aresteam-ports in the liner. 7 7 are cylinder-ports. 8 8 are exhaust-portsin the liner.

To each steam-chest 2 is fitted, as shown in Fig. 1, an apparatus of thekind shown in Figs. 2, 3, and 4. This apparatus comprises a piston 21,arranged to slide in a casing 22," the interior of which communicates bya branch pipe 23 with the steam-space 4 in the steam-chest 2. The piston21 is subjected on its outer side (11. e., the surface that faces to theleft in Fig. 2) to the pressure of the atmosphere and on its inner side(t'. a, the surface that faces to the right in Fig. 2) is subjected tothe same pressure that exists for the time being in the space 4 of thesteam-chest. The piston 21 is formed with a shoulder at 24, that servesto limit its outward movement. It is also formed or provided with aspindle or stem 25, that slides in a tubular guide 26,

a pressure in the steam-chest the piston 21 will move inward and itsstem 25, acting against the stem 31 of the steam-valve 29, will force vis in 1 these liners that the piston-valves 3 work in mosphericpressure, the piston 21 will move in the opposite direction, releasingthe steamvalve 29, which will then be forced uponits seat and will cutoff the supply of steam.

From the foregoing description it will be understood that although themain. supply of steam may be cut off at the regulator the steam-pressurein the space 4 of the steamchestcan never be reduced below that of theexternal atmosphere for the time being. At each stroke of theworking-piston of the engine steam will be drawn past the valve 29, thesteam-space 4, and one of the ports 7 until the cut-off takes place.This steam will then be expanded through the remainder of the strokeuntil the eXhaust-port'op'ens, whereupon there will be a slight inrushof air from the exhaust-pipe 5 On the return-stroke of theworking-piston of the engine the steam from the engine-cylinder 1 willbe expelled through the port 7, the exhaust-space 5, and

the exhaust-pipe 5 until the port '7 is again closed, whereupon theremaining steam will be compressed, and this compressed steam will actas a cushion to the working-piston of the engine until the port 7 isagain opened 1 to the steam-space 4. The steam so admitted will act as alubricant to the internal working parts.

The apparatus hereinbefore described tomatically comes into operationafter the main supply of steam has been cut ofi at the regulator andcontinues in operation until the engine comes to rest, effectuallypreventing the pressure in the steam chestor cylinder, or in each, ifapplied to more than one, falling appreciably below that of the externalatmosphere. When the engine comes to rest, the air-actuated plunger andsteam-valve will be automatically operated in the reverse di= rection bythe pressure within the steam chest or cylinder, and the automaticadmission of steam will thus be arrested.

This invention will enable a balance-valve to be used for thedistribution of steam to the cylinders of a locomotive withoutunnecessary strain being put on the piston rod and other parts of theengine.

Apparatus according to this invention may be used in connection withvalves other than I balanced valve'sfor instance, with valves placed onthe tops of cylinders and which do not fall from the faces.

\Vhat I claim is- 1. Apparatus for automatically admitting steam aloneto the steam-chest or to the cylinder of a locomotive-engine andcomprising a casing 22, provided with an inlet branch for steam andadapted to be connected to a steam pipe and an outlet branch adapted tobe connected to and with its interior in communica tion with said steamchest or cylinder, a valve 29, with stem 31, for controlling said steaminlet, and a piston 21, arranged to slide in said casing and providedwith a stem 25, adapted to act against said valve-stem 31 and open saidvalve when moved in one direction, said piston being subject on one sideto the pressure of steam in the casing and on the other side to thepressure of the external atmosphere, substantially as herein described.

2. The combination, with the cylinder 1 and steam-chest 2 ofalocomotive-engine, of a piston distributing-valve 11, arranged to'workin said steam-chest, an apparatus for automatically admitting steamalone to'said steamchest when the pressure therein falls below that ofthe external atmosphere, and an external steam-pipe 28, for connectingsaid apparatus to the locomotive-boiler, said apparatus comprising acasing 22, secured to said steam-chest and having an outlet 23 incommunication therewith and a steam-inlet in communication with saidpipe 28, a valve 29, with stem 31, for controlling said steam-inlet, anda piston 21, arranged to slide in said casing and provided with a stem25, capable 20 of acting against said stem 31 and opening said valvewhen moved in one direction, said 7 piston being subject on one side tothe pressname to this specification in the presence of 0 two subscribingwitnesses.

WALTER MAOKERSIE SMITH.

Witnesses:

ROBERT STIRLING,

14 Richmond Terrace, Gateshead-on-Tyne.

WILLIAM FORSTER,

10 Airey Terrace, Gatesheadmn-Tyne.

